Patients with chronic kidney disease dying for lack of their routine dialysis; 165,000 employees of the Palestine Authority unpaid for two and a half months; women selling jewellery for fuel or food ... the "humanitarian crisis" of the West Bank and Gaza is not a Darfur. And what most shocks Arabs and Muslims is that it stems from a conscious political decision by the world's only superpower. First, they say, you give us Iraq, now on the brink of civil war. Then this: the starving of a whole people.

The psychological and strategic linkage between Iraq and Palestine is far from new. But its latest, most intense phase began with the US invasion of Iraq - conceived by the Bush administration's pro-Israeli neoconservatives as the first great step in their region-wide scheme for "regime change" and "democratisation", whose consummation was to be an Arab-Israeli settlement. Indeed, professors Mearsheimer and Walt argue in their study, The Israel Lobby, that there very likely wouldn't have been an invasion at all but for Israel and, above all, its partisans inside the US.

But it had always been crystal clear that the more authentic any democracy Arabs or Palestinians did come to enjoy, US-inspired or not, the more their conception of a settlement would collide with the US-Israeli one. The point was swiftly proved, in the wake of Hamas's assumption of power, when President Bush declared: "We support democracy, but that doesn't mean we have to support governments elected as a result of democracy." And his administration set about engineering Palestinian "regime change" in reverse.

Its strategy found more or less willing accomplices - Europeans, Arab governments, the Palestinians themselves. But it was always going to be a perilous one; the more vigorously it was pursued in the face of the opposition that it was bound to encounter, the more likely it was to make of Palestine a crucible of trouble for its own people, the region and the world - very much like the one that other quasi-colonial western intervention had already made of Iraq.

The idea was to get the Palestinians, through collective punishment, to repudiate the very people they had just elected. Some do blame Hamas. But most of those blame America much more. If anything, sanctions have had the opposite effect from that intended, encouraging people to rally round the new government. Buoyed by its own popularity, on top of its electoral legitimacy, Hamas won't easily relinquish power - "not without a war", said Iyyad Sarraj, a Gaza psychologist.

Even if the US did succeed in bringing Hamas down, it would, like the overthrow of Saddam, be a catastrophic kind of success - plunging Palestine, too, into the chaos and internecine strife that is the antithesis of the modern, democratic, pro-western Middle East order the US is trying to build. It is clear that, with President Mahmoud Abbas's bombshell proposal for a referendum on the nature of a final peace raising the political stakes and with skirmishes in Gaza raising the military ones, war between Hamas and Fatah is eminently possible. It is far from clear that America's "side" could win. "If Fatah couldn't fight Hamas while it was still in power," said General Ilan Paz, the former head of Israel's civil administration in the territories, "how could it gain control with Hamas in power and itself disintegrated?"

Furthermore, chaos in the territories would open the way to militants, jihadists and suicide bombers from the rest of the world, just as it did in Iraq. Iran, the non-Arab country that is now the main state patron of Arab radicalism, was quicker than any Arab government to offer money to the new Hamas regime. An intrinsic part of its wider strategic and nuclear ambitions, Palestine now ranks among Iran's top foreign-policy priorities. Abbas says that Hizbullah and al-Qaida are already active in Gaza. From where, if not from such outsiders, have come the long-range Katyusha missiles that have begun to target southern Israel from Gaza? And if Hamas were driven from office, it would go underground again, resuming with a vengeance the resistance it has suspended.

As for the Arabs, they would be at least as subject to the fallout from Palestine as they are from Iraq's. Their discredited regimes hardly know what to fear more: the example of a Hamas democratically installed or undemocratically ousted. The first would encourage the ascension of their own Islamists. The civil war liable to result from the second would arouse even more dangerous passions among them. Broadly speaking, Hamas has Arab, especially Islamist, public opinion on its side, and the more the regimes defer to the US in its anti-Hamas campaign, the greater discredit they will fall into.

For Rami Khouri, a leading Beirut columnist, the Palestine cause risks being transformed from a "national" into a "civilisational" one, with "potentially dangerous linkages between events in Palestine-Israel and the rest of the Middle East".

"Hundreds of thousands of young people will feel duped and betrayed. The wellspring of support for Hamas- and Muslim Brotherhood-style democratic engagement will slowly dry up in favour of more intense armed struggle. They will stop wasting time trying to redress grievances through peaceful, democratic politics or diplomacy ... Bringing down the Hamas-led Palestinian government will bring further radicalisation, resistance and terrorism across the region." Well aware of this resonance, the Palestinian finance minister, Omar Abdul Razeq, warned: "The entire region will catch fire if the Palestinian people are pushed to a situation where they have nothing to lose."

Suddenly this month the Bush administration seemed to grasp something of the perils it is courting. And those US-engineered privations of Gaza were too scandalous to ignore. At a meeting of the Quartet (the EU, the US, the UN and Russia), it offered $10m in emergency medical aid. The largesse was paltry and grudging, but at least it seemed to indicate that Washington had given up hope of bringing about immediate "regime change" via economic ruin. Gideon Levy, a pro-Palestinian Israeli commentator, was even moved to say: "Hamas is winning."

Hardly. For the only substantive way in which it could be said to be doing that would be if the US started drawing the right conclusions from this spectacularly unwelcome result of Arab democratisation - the most important of which is that, were it not for US policies, Hamas would never have won the elections.

But that would require a fundamental, revolutionary change of heart. In the opinion of Mearsheimer and Walt, the extraordinary US attachment to Israel - that moral and strategic "burden" - makes such a change impossible any time soon. So the fear must now be that, long before this could happen, the Middle East's "dangerous linkages" will assert themselves even more dangerously than before, and that those two ongoing crises - Palestine and Iraq, which the attachment did so much to engender - will be joined, and fused into a single mega-crisis, by a third: when, on its protege's behalf, the Bush administration goes to war against Iran.

· David Hirst reported from the Middle East for the Guardian from 1963 to 2001